In a letter to a constituent dated Oct. 2, Coburn said his staff had reached out to the office of Maricopa County Sheriff Joe Arpaio in Phoenix after making a promise to tea-party activist Miki Booth at an Aug. 7 town hall appearance in Claremore, Okla. At the campaign event, Booth was seen on video confronting the senator about a letter she had written to him.

“My staff has reached out to Sheriff Arpaio’s office,” Coburn wrote in the constituent letter. “However, I have yet to be presented any credible evidence to demonstrate President Obama was not born in Hawaii.”

From there, Coburn cited Obama being placed on state ballots for president as proof Obama’s birth certificate is genuine.

“Furthermore, all 50 states saw fit to put Mr. Obama on their ballots in 2008 and again in 2012,” Coburn wrote. “This includes Arizona, which was recently provided verification of President Obama’s birth by Hawaii. I remain open to hearing and reviewing any supporting evidence.”

However, Mike Zullo, lead investigator for Sheriff Arpaio’s law enforcement investigation into Obama’s eligibility, insists Coburn has yet to see the evidence his team has uncovered indicating the document the White House posted as Obama’s birth certificate is a forgery.

“I was initially contacted by Ken Ashton, an aide to Sen. Coburn in Sen. Coburn’s Washington office, on Sept. 4,” Zullo explained to WND. “I provided Ashton at his request, an overview of the sheriff’s investigation, focusing on the document fraud.”

Coburn’s office has not replied to WND’s request for comment.

Zullo told WND he emphasized to Ashton the sheriff was not investigating the president but the long-form birth certificate released by the White House April 27, 2011, to determine if that document was legitimate.

“I told Ashton that it would be appropriate for Sen. Coburn to contact Sheriff Arpaio directly to fulfill the commitment Coburn had made to his constituents,” Zullo said. “I explained Sheriff Arpaio was prepared and looking forward to answering any questions Coburn might have.”

Zullo documented his discussion with Ashton in an internal memo sent to Arpaio’s office Sept. 4. Zullo told Arpaio that he expected Coburn would contact the sheriff to request access to the evidence after Ashton and Coburn had an opportunity to study the overview.

Two weeks later, Zullo received a second phone call from Ashton in which Ashton seemed intent to emphasize the fact that he had called Arpaio’s office Sept. 4 in his capacity as an investigative aide to Coburn.

“I told Ashton that Coburn should speak directly to Sheriff Arpaio, because the sheriff had to make the decision to release evidence from the investigation,” Zullo recalled.

“I specifically pointed out to Ashton he would not be able to use his phone call to me as a substitute for Sen. Coburn talking directly to Sheriff Arpaio.”

Zullo told WND he felt Ashton’s second phone call was disingenuous, almost as if Ashton wanted Zullo to agree to a cover story.

“At the conclusion of the phone call, I felt Coburn’s office was attempting to use Ashton’s phone call as evidence that Coburn contacted the sheriff’s office,” Zullo said, “when the truth is Coburn never contacted Sheriff Arpaio, and Coburn never requested any evidence be provided to him for his inspection.”

Zullo said the episode was typical of the repeated frustrations the sheriff has experienced trying to get Congress to look at the birth certificate evidence.

“Ashton was trying to create the illusion that somehow the Maricopa County Sheriff’s Office had not provided Sen. Coburn with any credible evidentiary information, even though Ashton never requested to see the evidence,” Zullo said.

“Even if Ashton had requested to see the evidence, the Maricopa County Sheriff’s Office would not blindly send out the evidence without first requiring Sen. Coburn to talk with the sheriff so the sheriff could make a determination whether or not it was appropriate to release the evidence to the senator’s office.”

Zullo’s final conclusion was that Coburn’s office was just engaging in politicking, and Ashton only wanted to create “the illusion the evidence had been examined.”

“The truth appears to be that Sen. Coburn has no serious interest in conducting an honest evaluation of whether or not Obama’s birth certificate is genuine, or the computer-generated forgery we have concluded the document is,” Zullo said.